#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

/* psrfits2fb - converts PSRFITS files into sigproc format */
// CANNOT USE OPTIMISATION !!!!!!!!!


#include "filterbank.h"
#include <fitsio.h>

unsigned char reverseSamplesInByte(unsigned char c);

#define BUFFER 4096

void psrfits2fb(FILE *input, FILE *output,char *filename) /* includefile */
{  
	fitsfile *fp;
	int status=0;
	int nsubint=0;
	int samplesperbyte=0;
	int samplespersubint=0;
	long numrows;
	int colnum;
	int i,pol,j,npol,sample,initflag=0,s;
	int subint;
	char *val2,*valI;
	char temp;
	char nval = '0';
	float *values;

	npol = nifs;
	fits_open_file(&fp,filename,READONLY,&status);
	fits_report_error(stderr,status);

	if (nbits > 8){
		fprintf(stderr,"Error: psrfits2fb.c does not support nbits > 8\n");
		exit(1);
	}


	// Find nsubint
	fits_movnam_hdu(fp, BINARY_TBL, "SUBINT", 1, &status);
	fits_get_num_rows(fp, &numrows, &status);
	fits_read_key(fp, TINT, "NSBLK", &samplespersubint, NULL, &status );
	nsubint = (int)numrows;
	samplesperbyte = (int)(8/nbits);

	val2 = (char *)malloc(sizeof(char)*samplespersubint*npol*nchans/samplesperbyte+1);
	values = (float *)malloc(sizeof(float)*nchans);

	for (i=0;i<samplespersubint*npol*nchans/samplesperbyte+1;i++)
		val2[i] = 0;

	// Read data
	fits_get_colnum(fp,CASEINSEN,"DATA",&colnum,&status);
	for (subint=1;subint<=nsubint;subint++)
	{
		fits_read_col_byt(fp, colnum, subint, 1LL, npol*nchans/samplesperbyte*samplespersubint, nval, val2,&initflag, &status);
		//    fprintf(stderr,"%x %d %d %d %d %d\n",fp, colnum, subint,npol*nchans/samplesperbyte*samplespersubint, nval, val2[0]);

		if (flip_band){
			if (npol != 1){
				fprintf(stderr,"Npol>1 data not handled when bw is +ve\n");
				fprintf(stderr,"see 'psrfits2fb.c'\n");
				exit(1);
			}

		// we have to flip the band... here I assume data is only 1 poln
		// otherwise it gets rather expensive and complicated.
		// also assumes nbits <= 8

			//ASSUMES npol=1. This is very important.
			int nflip = nchans/samplesperbyte;
			unsigned char tmp;
			int c;
			for (i=0;i<samplespersubint;i++) {
				// for each sample, flip all the bytes.
				char* p1=val2 +(i*nflip);
				char* p2=val2 +((i+1)*nflip-1);
				while (p1<p2){
					tmp=*p1;
					*p1 = *p2;
					*p2 = tmp;
					p1++;
					p2--;
				}
			}
		} else {
			// Here the bits in the byte (per sample) are reversed but the bytes are not.
			for (i=0;i<npol*nchans/samplesperbyte*samplespersubint;i++) val2[i]=reverseSamplesInByte(val2[i]); 
		}



		fwrite(val2,sizeof(char),npol*nchans/samplesperbyte*samplespersubint,output);
	}

	fits_close_file(fp,&status);
	fits_report_error(stderr,status);
	free(val2);
	free(values);
}


unsigned char reverseSamplesInByte(unsigned char c)
{
	/**
	 *  Reverses the samples in a char (a byte), by using a 256-element
	 *  look-up table. This means 01100011 becomes 11000110.
	 *  /param c The byte, as a char, to be reversed.
	 *  /return The reversed byte.
	 */


	static const unsigned char BitReverseTable256[] = 
	{
		0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, 
		0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 
		0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, 
		0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, 
		0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, 
		0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
		0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, 
		0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
		0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
		0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, 
		0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
		0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
		0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, 
		0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
		0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, 
		0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
	};

	unsigned char r = 0;
	switch(nbits){
		case 1:
			r = BitReverseTable256[c & 0xff];
			break;
		case 2:
			r=(c&3)<<6 | (c&12)<<2 | (c&48)>>2 | (c&192)>>6;
			break;
		case 4:
			r=(c&0x0F)<<4 | (c&0xF0)>>4;
			break;
		default:
			// 8 bits or more: no internal byte swapping required.
			r=c;
			break;
	}
	return r;

}
